K8SPG-894: bring back major-upgrade test but remove restores from it

[eleo007]

CHANGE DESCRIPTION

Problem:

1. The upgrade -> backup -> restore sequence sometimes results in cluster being not able to start. That is why we need to skip restore in upgrade tests till the issue is fixed.

2. The image tags patterns have changed due to the usage of official images.

3. Removing PG12 from upgrade as it is not supported any more.

Cause:
Short explanation of the root cause of the issue if applicable.

Solution:
Short explanation of the solution we are providing with this PR.

CHECKLIST

Jira

• Is the Jira ticket created and referenced properly?
• Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• Is an E2E test/test case added for the new feature/change?
• Are unit tests added where appropriate?

Config/Logging/Testability

• Are all needed new/changed options added to default YAML files?
• Are all needed new/changed options added to the Helm Chart?
• Did we add proper logging messages for operator actions?
• Did we ensure compatibility with the previous version or cluster upgrade process?
• Does the change support oldest and newest supported PG version?
• Does the change support oldest and newest supported Kubernetes version?